Sports cats or decat ??

[montecristo8]

Hi all,
After years of avidly reading this forum, this is my first message/question I may ask the community.

Owner of a 1M for the last 3 years, I only use my car on week-ends and only for street use. I immediately got rid of the stock exhaust in favor of a catback Akrapovic exhaust with valve.

The sound is great but could be more present/alive. 2 options here : either catless or 200 cel sports cats DP. My mechanic would like me to go catless and tells me he never installed sports cats on a 1M (and he saw quite a few of them).

Either way, I will need a ECU flash. The catless option caught my interest but I am scared of the noise and smell (+ inspection). Don't know on the other hand if the sports cats option (more pricey) will really make a drastic change regarding sound.

Let me know what you think !

Thanks.

David.

[PRTSB1M]

Originally Posted by montecristo8

Hi all,
After years of avidly reading this forum, this is my first message/question I may ask the community.

Owner of a 1M for the last 3 years, I only use my car on week-ends and only for street use. I immediately got rid of the stock exhaust in favor of a catback Akrapovic exhaust with valve.

The sound is great but could be more present/alive. 2 options here : either catless or 200 cel sports cats DP. My mechanic would like me to go catless and tells me he never installed sports cats on a 1M (and he saw quite a few of them).

Either way, I will need a ECU flash. The catless option caught my interest but I am scared of the noise and smell (+ inspection). Don't know on the other hand if the sports cats option (more pricey) will really make a drastic change regarding sound.

Let me know what you think !

Thanks.

David.

1M factory downpipes came with high-flow catalytic converters, so replacing them with "sport cats" likely won't change anything in terms of sound. Did you install the Akrapovic mid-pipes with your previous exhaust upgrade?

[ayao]

I agree with @PRTSB1M.
Although I have never experimented with changing the stock DPs, I found that a midpipe (Maddad, in my case) had the biggest impact on the sound. The axleback alone was not enough of a change for me but midpipe + axleback was just right.

[Ewok]

Another option may be just to go catless DP eg. Akrapovic DP , but retain stock midpipe and axleback (No CEL since you retain the secondary cats in the midpipe.)

[montecristo8]

Hi, thanks a lot for your answers ! PRTSB1M Yes I have the Akrapovic midpipe (Evolution exhaust line).

Considering the price of HSJ sports cats, I would not want to spend 2k for a device that won't change much (or at all) the sound in the cabin.

Replacing the midpipe with a N55 or else could be a solution. In your opinion, would it change drastically the sound vs my current exhaust system ?

Thanks a lot for all these info and for your help !

[PRTSB1M]

Originally Posted by montecristo8

Hi, thanks a lot for your answers ! PRTSB1M Yes I have the Akrapovic midpipe (Evolution exhaust line).

Considering the price of HSJ sports cats, I would not want to spend 2k for a device that won't change much (or at all) the sound in the cabin.

Replacing the midpipe with a N55 or else could be a solution. In your opinion, would it change drastically the sound vs my current exhaust system ?

Thanks a lot for all these info and for your help !

I am currently running the factory downpipes with a MadDad mid-pipe and the Akrapovic rear section; the MadDad has smaller resonators than the Akrapovic mid-pipes. I'm pretty happy with the sound of this setup, but the Akrapovic rear section has a larger diameter pipe than the factory rear section and doesn't mate perfectly to the MadDad.

I think the N55 mid-pipe might give a little more sound, but you will need the reducer flange/gasket to mate it to the larger diameter Akrapovic rear section.

When I get the motivation to tear the car apart again, I will be replacing the factory downpipes and MadDad mid-pipe with Akrapovic parts.

[ayao]

I had an N55 midpipe before the Maddad and it was not loud enough (for me.)

I do not know what Maddad does with the resonators that replace the N54 midpipe cats but the difference in volume is very noticeable.

Originally Posted by montecristo8

Hi, thanks a lot for your answers ! PRTSB1M Yes I have the Akrapovic midpipe (Evolution exhaust line).

Considering the price of HSJ sports cats, I would not want to spend 2k for a device that won't change much (or at all) the sound in the cabin.

Replacing the midpipe with a N55 or else could be a solution. In your opinion, would it change drastically the sound vs my current exhaust system ?

Thanks a lot for all these info and for your help !

[montecristo8]

Thanks a lot for your replies. I don't know if it would make any sense to replace my Akra mid pipes with Maddad ones. The only way to improve my system would be to install catless DP with an ECU flash.

[montecristo8]

Do you know where I could find a Maddad midpipe by any chance ? I may give a try to that solution (instead of the Akra midpipe). Depite my Google search, I cannot find the Maddad midpipe.

[PRTSB1M]

Originally Posted by montecristo8

Do you know where I could find a Maddad midpipe by any chance ? I may give a try to that solution (instead of the Akra midpipe). Depite my Google search, I cannot find the Maddad midpipe.

I'm pretty sure they are no longer made by the original manufacturer. The one I got came from Stromung in Huntington Beach, CA. The number listed on their contact page is the same one that's on the shipping label from the one I got back in 2020.

http://www.stromungexhaust.com/contact-us.html

Found a link on the wayback machine: https://web.archive.org/web/20150324..._p/md135mp.htm

[ayao]

Originally Posted by montecristo8

Do you know where I could find a Maddad midpipe by any chance ? I may give a try to that solution (instead of the Akra midpipe). Depite my Google search, I cannot find the Maddad midpipe.

Here are a few links to take a look at.
https://www.1addicts.com/forums/show....php?t=1881501
https://www.1addicts.com/forums/show....php?t=1334855
https://www.1addicts.com/forums/showthread.php?t=632402

Long story short, they are no longer made but the plans still exist and with the right amount of interest (or $) the original manufacturer might be persuaded to dust off the jig.

These do surface occasionally on the forum classified sections as well.

[E46M3forRay]

Originally Posted by montecristo8

Either way, I will need a ECU flash. The catless option caught my interest but I am scared of the noise and smell (+ inspection). Don't know on the other hand if the sports cats option (more pricey) will really make a drastic change regarding sound.

Let me know what you think !

Have you considered ditching the akra axle back and go with a straight pipe or race exhaust ?

Supersprint makes a race exhaust for the 1M.
https://www.ecstuning.com/b-superspr...er/046206~ssp/

I also have the akra full catback exhaust and I think it's just enough sound for me. The valve rattle annoys me at cold startup though.